Process of recovering molybdenum from molybdenite



IPBQUB UNITED STATES PATENT OFFICE.

GEORGE W. SARGENT, OF PITTSBURGH, AND JOSEPH W. WEITZENKORN, 0F WASI-L INGTON, PENNSYLVANIA.

PROCESS OF REGOVERING MOLYBDENUM FROM MOLYBDENITE.

No Drawing. Application filed June 14,

To all whom it may concern:

Be it known that I, Gnonor. W. SARGENT, a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, and Josnrrr W. VVEITZENKORN, a resident of Washington, in the county of Washington and State of Pennsylvania, have invented a new and useful Improvement in Processes of Recovering Molybdenum from Molybdenite, of which the following is a specification.

The invention relates to the recovery of molybdenum from molybdenite.

Until recently molybdenum has been classed as a rare or semi-rare metal, and its use has been limited to products in which, for the most part, the cost of manufacture is not the controlling or prime factor. Chiefly because the metal was rare and its use so limited, the processes heretofore developed for its recovery from molybdenite, that is to say, molybdenum sulfid ore, are not such as may be used to economically recover the metal in large quantities.

Of late years large deposits of molybdenite have been discovered, so that there are now available sources of molybdenum of such extent that the metal may, if economi cally recovered from the ore, be extensively used in large quantities for various purposes, as for example in the manufacture of ferrous alloys such as steel and iron.

It is, accordingly, the object of the invention to provide a method whereby molybdenum, substantially free from sulfur, may be economically recovered from molybdenite, and also to provide a method for economically producing directly from molybdenite a molybdenum alloy low in sulfur.

The invention, as far as concerns its broader aspects, is predicated upon our discovery that molybdenite readily combines with an oxid of manganese in an exothermic reaction which evolves almost sufficient heat to render the continued reaction self sustaining after the molybdenite and the metallic oxid have been heated to the reaction temperature.

In the preferred practice of the invention molybdenite is caused to combine with manganese dioxid in the presence of a reducing agent such as carbon, the reaction being carried on at an elevated temperature in any well known or desired type of furnace or crucible. However, the process may be, and

Specification of Letters Patent. Patent d De 27 1921 1920. Serial No. 388,785.

preferabl is, practised in an electric furnace of t e reslstor are or semi-arc resistor type.

Prior to its being charged into the furnace, the molybdenite, prpsl ed otherwise reduced to substantially a p oyvg er state, is mixed wlth powdered manganese dioxid and a sultable reducing agent such as carbon in the form of charcoal, coke and the like. V Vhen the proper proportions of these materials are used it has been found that at a temperature of about 2000 F. the following reaction takes place It it believed that in the first step in this reaction the manganese dioxid combines exothermlcally with the molybdenite to form a manganese molybdenum sulfid compound, which is thereafter reduced by the carbon. Whatever the steps in the reaction may be, it has been found that carbon dioxid passes off as a gas, that substantially pure molybdenum settles to the bottom of the furnace, and that a low melting point fluid slag of manganese sulfid separates from, and floats upon, the molybdenum.

After the materials have been heated to the temperature required for starting the reaction, the exothermic character of the reaction makes it necessary to apply little if any additional heat. Before tapping the furnace for final cleaning, the molten mass may, if found necessary, be cleaned up by the addition of carbon or manganese or an oxid thereof. However, it has been found that, if the mixture is properly proportioned at the beginning, little if any cleaning up is required, the condition of the slag under proper mix conditions being such that the slag readily throws out the metallic molybdenum, retaining little if any of the metal.

If it is desired to recover the molybdenum in the form of a ferro-alloy for subsequent use in the manufadtiir'eof alloy steel and iron, iron eihe..-. enn.qt filiegajerrin etc., may bepl gedwinmthefl mix, the amount of iron thiis' added depending upon the proportion of iron and molybdenum desired in the ferro-molybdenum. The process may be otherwise practised as previously described, it having been found that the molten iron readily mixes or alloys with the molten molybdenum so that there results a ferromolybdenum alloy of predetermined proportions obtained directly from the molyb- (lenite.

As thus far described, the process has been 5 explained solely with reference to the use of manganese dioxid and carbon as the materials to be combined with molybdenite in the initial mix. The invention also contemplates, as a step in the process, the combining of an oxid of manganese and molybdenite without carbon. By forming a mix of thesetwo materials and heating it in the manner described, there is eliminated a large portion of the sulfur in the form of sulfur dioxid, and a manganese-molybdenum-sulfid compound is formed, which can be further reduced to metallic molybdenum by the addition of carbon, or which may be used as a starting point to make other molybdenum compounds.

The invention also contemplates the simultaneou recovery of molybdenum from molybdenite and the manufacture of an alloy such as molybdenum steel. For this purpose an oxid of manganese and molybdenite may be charged directly into a steel manufacturing furnace, such as an electric or open hearth furnace. Sufficient carbon to reduce the manganese-molybdenum sulfid 30; may be introduced with the manganese and molybdenite, or the carbon of the steel-furnace charge may be relied upon to reduce such compound. In the latter case, the fur- ,nace charge will contain ufficient carbon to 35 accomplish both the reduction of the manganese-molybdenum sulfid compound and to satisfy the usual requirement in the manufacture of the steel. lVhen the molybdenum is recovered in this manner it alloys directly with the teel.

In actual practice of the invention it has been found that molybdenum and ferro-molybdenum may be readily produced containing less than 0.10% sulfur. The materials utilized in the process are abundant and cheap, and the heat required for carrying out the process is very small due to the exothermic character of the reaction. All of these considerations contribute to the practical and economic character of the process, by which large quantities of molybdenum may be recovered for the rapidly increasing uses to which it is being put.

\Ve claim:

1. A step in the process of recovering molybdenum from molybdenite, which consists in causing an oXid of manganese to react with molybdenite.

2. The process of recovering molybdenum from inolybdenite, which consists in causing an oxid of manganese to react with molybdenite in the presence of a reducing agent.

3. The process of recovering molybdenum from molybdenite, which consists in causing. manganese dioxid to react with molybdenite in the presence of carbon.

4. The process of producing ferro-molybdenum directly from molybdenite, which consists in causing an oxid of manganese to react with molybdenite in the presence of iron and a reducing agent.

5. The process of recovering metal from a sulfid ore thereof, which consists in causing an oxid of manganese to react with the sulfid ore in the presence of a reducing agent.

In testimony whereof, we have hereunto set our hands.

GEORGE W. SARGENT. JOSEPH W. WEITZENKORN.

Witnesses MARX Hanson, WM. H. Wars. 

